Leading article: Nato must not be seduced into prolonging the conflict in Libya

Three weeks after the first UN-authorised air strikes on eastern Libya, there is a distinct sense that the conflict is stagnating. The rationale for intervening, and the haste with which this was done, remains as valid today as it was then.

Without such prompt and decisive action, the bloodbath forecast for Benghazi could well have come to pass. The rebel movement might have been crushed even before it had had a chance to coalesce. There is no latitude for "what ifs" here.

As time has passed, however, certain realities have become clearer, and not all of them are welcome. One is the motley nature of the opposition to the Gaddafi clan. Given the repressive nature of Gaddafi's rule, there should be no surprise that those trying to unite against him seem ill-prepared either to fight or, were they to prevail, to govern.

Another is Gaddafi's continuing determination and strength. At the start of the intervention, his forces appeared to be in full retreat; the way seemed to be open for opposition forces to consolidate their gains in the east and speed to Tripoli. Paradoxically, the day before the first air strikes saw the first serious setbacks for the opposition. Since then, control of the western city of Misrata has been in almost continuous contention, and a shifting front line has established itself between Ajdabiya and Brega in the east.

The command structure for the intervention has also seen changes. The United States has relinquished overall command to Nato, with the British and French reportedly not always seeing eye to eye over targets. Inevitably, and not necessarily connected with this, mistakes have been made. In the latest, 13 people were reported killed as a result of a strike on rebel tanks. A Nato spokesman said the alliance had been unaware that the opposition had tanks at their disposal, so assumed they belonged to government forces. He expressed regret for the deaths, but refused to apologise – insisting "our job is to protect civilians".

That formulation – rightly – underlines the limitations of the intervention. At the start, the air strikes had the effect of bolstering the opposition. But the UN resolution did not underwrite the use of force as assistance to the rebels; the focus was on the protection of civilians. Now, with the no-fly zone in operation and the opposition controlling more hardware, the fighting, in the east at least, is more evenly balanced. Although some have mooted supplying arms to the rebels, it may be that they have now received as much help as UN resolution 1973 allows. Regime change might have been desirable, but it was never the official purpose of the intervention.

If, as it appears, the conflict is stagnating, with Gaddafi still holding sway in the west and the opposition holding almost uncontested power in the east, the time may be approaching when consideration should be given to an outcome short of a complete opposition victory. It may be premature to talk about the division of Libya, but a de facto recognition of two areas under separate control might be the optimum interim solution. There is no sign yet that this would be acceptable to the two sides, and Nato might have to continue to fund and maintain the no-fly zone even if it were, but an uneasy peace might be preferable for everyone to an indefinite war in the desert.